Wilke Claudia, Barkleit Astrid, Stumpf Thorsten, Ikeda-Ohno Atsushi
Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, P.O. Box 510119, 01314 Dresden, Germany.
Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, P.O. Box 510119, 01314 Dresden, Germany.
J Inorg Biochem. 2017 Oct;175:248-258. doi: 10.1016/j.jinorgbio.2017.07.020. Epub 2017 Aug 4.
In case radioactive materials are released into the environment, their incorporation into our digestive system would be a significant concern. Trivalent f-elements, i.e., trivalent actinides and lanthanides, could potentially represent a serious health risk due to their chemo- and radiotoxicity, nevertheless the biochemical behavior of these elements are mostly unknown even to date. This study, therefore, focuses on the chemical speciation of trivalent f-elements in the human gastrointestinal tract. To simulate the digestive system artificial digestive juices (saliva, gastric juice, pancreatic juice and bile fluid) were prepared. The chemical speciation of lanthanides (as Eu(III)) and actinides (as Cm(III)) was determined experimentally by time-resolved laser-induced fluorescence spectroscopy (TRLFS) and the results were compared with thermodynamic modeling. The results indicate a dominant inorganic species with phosphate/carbonate in the mouth, while the aquo ion is predominantly formed with a minor contribution of the enzyme pepsin in the stomach. In the intestinal tract the most significant species are with the protein mucin. We demonstrated the first experimental results on the chemical speciation of trivalent f-elements in the digestive media by TRLFS. The results highlight a significant gap in chemical speciation between experiments and thermodynamic modeling due to the limited availability of thermodynamic stability constants particularly for organic species. Chemical speciation strongly influences the in vivo behavior of metal ions. Therefore, the results of this speciation study will help to enhance the assessment of health risks and to improve decorporation strategies after ingestion of these (radio-)toxic heavy metal ions.
万一放射性物质释放到环境中，它们进入我们的消化系统将是一个重大问题。三价f元素，即三价锕系元素和镧系元素，由于其化学毒性和放射毒性，可能构成严重的健康风险，然而即使到目前为止，这些元素的生化行为大多仍不为人知。因此，本研究聚焦于三价f元素在人体胃肠道中的化学形态。为模拟消化系统，制备了人工消化液（唾液、胃液、胰液和胆汁）。通过时间分辨激光诱导荧光光谱法（TRLFS）实验测定了镧系元素（以Eu(III)计）和锕系元素（以Cm(III)计）的化学形态，并将结果与热力学模型进行了比较。结果表明，口腔中以磷酸盐/碳酸盐为主的无机物种占主导，而在胃中主要形成水合离子，胃蛋白酶的贡献较小。在肠道中，最主要的物种是与蛋白质粘蛋白结合的物种。我们通过TRLFS展示了三价f元素在消化介质中化学形态的首个实验结果。结果突出了实验与热力学模型在化学形态方面的显著差距，这是由于热力学稳定性常数尤其是有机物种的稳定性常数有限。化学形态强烈影响金属离子的体内行为。因此，该形态研究的结果将有助于加强对健康风险的评估，并改进摄入这些（放射性）有毒重金属离子后的促排策略。
